	US 12,308,769 B1
	Adjustable speed generator motor system with full power converter
Akira Bando, Tokyo (JP); Takahiko Kikui, Tokyo (JP); Kenta Watanabe, Tokyo (JP); Yasuhiro Kiyofuji, Tokyo (JP); Masakazu Ishikawa, Tokyo (JP); Tomomichi Ito, Tokyo (JP); Masaya Ichinose, Tokyo (JP); Jun Narushima, Tokyo (JP); and Hikaru Meguro, Tokyo (JP)
Assigned to HITACHI MITSUBISHI HYDRO CORPORATION, Tokyo (JP); Hitachi, Ltd., Tokyo (JP); and HITACHI INDUSTRIAL PRODUCTS, LTD., Tokyo (JP)
Appl. No. 18/685,065
Filed by HITACHI MITSUBISHI HYDRO CORPORATION, Tokyo (JP); Hitachi, Ltd., Tokyo (JP); and HITACHI INDUSTRIAL PRODUCTS, LTD., Tokyo (JP)
PCT Filed Aug. 23, 2021, PCT No. PCT/JP2021/030855 § 371(c)(1), (2) Date Feb. 20, 2024, PCT Pub. No. WO2023/026335, PCT Pub. Date Mar. 2, 2023.
Int. Cl. H02P 21/00 (2016.01); H02P 21/22 (2016.01)

CPC H02P 21/22 (2016.02)

10 Claims

1. An adjustable speed generator motor system with full power converter, the system comprising:

two 3-level converters each having a positive terminal (P terminal), a negative terminal (N terminal), and an intermediate potential terminal (C terminal) provided on a direct current (DC) side, and a 3-phase alternate-current (AC) terminal provided on an AC side, the two 3-level converters configured to switch and output 3-level potentials of a positive terminal potential (+1 mode), a negative terminal potential (−1 mode), and an intermediate potential terminal (0 mode) to the 3-phase AC terminal, the two 3-level converters being a first 3-level converter with the 3-phase AC terminal connected to an AC system via an inductive element and a second 3-level converter with the 3-phase AC terminal connected to an AC rotating machine via an inductive element, positive terminals (P terminals), negative terminals (N terminals), and intermediate potential terminals (C terminals) of the two 3-level converters being connected back-to-back;

a positive capacitor (CBP) connected between the positive terminal (P terminal) and the intermediate potential terminal (C terminal);

a negative capacitor (CBN) connected between the intermediate potential terminal (C terminal) and the negative terminal (N terminal);

a first current detector configured to detect a 3-phase AC current (ITU, ITV, ITW) of the first 3-level converter;

a first current vector calculator configured to receive the 3-phase AC current and a voltage phase of the AC system and to detect a transvers-axis component (ITQ_FB) and a direct-axis component (ITD_FB) of the 3-phase AC current;

a first DC current regulator including at least proportional elements and integral elements and configured to match a transvers-axis current command (ITQ_REF) to the first 3-level converter with the transvers-axis component (ITQ_FB) of the 3-phase AC current, to match a direct-axis current command (ITD_REF) to the first 3-level converter with the direct-axis component (ITD_FB) of the 3-phase AC current, and to output a voltage command for the transvers-axis component and the direct-axis component;

a first AC voltage command calculator configured to receive the voltage command for the transvers-axis component and the direct-axis component from the first DC current regulator and to output a first 3-phase AC voltage command (α_TU, α_TV, α_TW);

a first PWM modulator configured to receive the first 3-phase AC voltage command and to output a first 3-level potential command (M_TU1, M_TV1, M_TW1);

a first pulse generator configured to receive the first 3-level potential command and to output a firing pulse to a P element, a PC element, an NC element, and an N element, the P element, the PC element, the NC element, and the N element being four electronic switches connected in four series in a direction from the positive terminal (P-terminal) to the negative terminal (N-terminal) and constituting the first 3-level converter;

a second current detector configured to detect a 3-phase AC current (IMU, IMV, IMW) of the second 3-level converter;

a second current vector calculator configured to receive the 3-phase AC current and a voltage phase of the AC rotating machine and to detect a transvers-axis component (IMQ_FB) and a direct-axis component (IMID_FB) of the 3-phase AC current;

a second DC current regulator including at least proportional elements and integral elements and configured to match a transvers-axis current command (IMQ_REF) to the second 3-level converter with a transvers-axis component (IMQ_FB) of the 3-phase AC current, to match a direct-axis current command (IMD_REF) to the second 3-level converter with a direct-axis component (IMID_FB) of the 3-phase AC current, and to output a voltage command for the transvers-axis component and the direct-axis component;

a second AC voltage command calculator configured to receive the voltage command for the transvers-axis component and the direct-axis component from the second DC current regulator and the rotation phase of the AC rotating machine and to output a second 3-phase AC voltage command (α_MU, α_MV, α_MW);

a second PWM modulator configured to receive the second 3-phase AC voltage command and to output a second 3-level potential command (M_MU1, M_MV1, M_MW1);

a second pulse generator configured to receive the second 3-level potential command and to output a firing pulse to four electronic switches constituting the second 3-level converter;

a first mode command switcher provided independently for 3-phase AC currents of the first 3-level converter, the first mode command switcher configured to receive the 3-phase AC current (ITU, ITV, ITW), to output a third 3-level potential command (M_TU2, M_TV2, M_TW2) to the first 3-level converter, to set the third 3-level potential command (M_TU2, M_TV2, M_TW2) to the negative terminal potential (−1 mode) when the 3-phase AC current (ITU, ITV, ITW) exceeds a threshold (I1) in an outflow direction from the first 3-level converter, to output the third 3-level potential command (M_TU2, M_TV2, M_TW2) as the positive terminal potential (+1 mode) when the 3-phase AC current (ITU, ITV, ITW) exceeds the threshold (I1) in an inflow direction to the first 3-level converter, and to switch from the first 3-level potential command (M_TU1, M_TV1, M_TW1) to the third 3-level potential command (M_TU2, M_TV2, M_TW2) independently for three phases when an absolute value of the 3-phase AC current (ITU, ITV, ITW) exceeds the threshold (I1) to output a fourth 3-level potential command (M_TU, M_TV, M_TW) to the first PWM modulator;

a first AC current command calculator configured to receive the transvers-axis current command (ITQ_REF) and the direct-axis current command (ITD_REF) to the first 3-level converter and the voltage phase of the AC system and to output a first 3-phase AC current command (ITU_REF, ITV_REF, ITW_REF); and

a first AC current regulator provided for each 3-phase AC current of the first 3-level converter and configured to match the 3-phase AC current (ITU, ITV, ITW) with the first 3-phase AC current command (ITU_REF, ITV_REF, ITW_REF) to output a second AC voltage command, the first AC current regulator having proportional elements four times or more than the proportional elements of the first DC current regulator, and to energize the second AC voltage command independently for each phase to the first 3-phase AC voltage command (α_TU, α_TV, α_TW) to output the second AC voltage command to the first PWM modulator.